Obstruction release for grinding machines



June 1 1926. 1,587,104

W. W. DRYDEN OBSTRUCTION RELEASE FOR GRINDING MACHINES Filed August 30, 1924 2 Sheets-Sheet 1 l 1;!V EN T OR. Vz'lizm HD4709):

ARNEY.

June 1 1926. 1,587,104

W. W. DRYDEN DESTRUCTION RELEASE FOR GRINDING MACHINES Filed August 30, 1924 2 Sheets-Sheet 2 BY ,6 xi

A TTOI Patented June 1, 1926.

. issuer UNITED STATES v PATEf"Ff"-ll.

WILLIAM W. DRYDIEN, OF LOUISVILLE, KENTUCKY, ASSIGNOR TO W'AL'IEB F. STIMP- SON, OF LOUISVILLE, KENTUCKY.

OBSIBUGTION RELEASE FOR, GRIIIIDING MACHINES.

Application filed August 30, 1924. Serial No. 735,072.

This invention relates to grinding machines, and has for its principal object the provision of means to automatically disengage the grinding mechanism from the driv ing mechanism, whenever obstructions, such as nails, stones or the like, engage with the grinding burrs of the grinding mechanism, whereby the driving mechanism may continue to rotate freely while the grinding elements remain at rest until the obstruction is removed.

Another object of the invention is the arrangement of a pivoted driving plate intermediate the driving mechanism of the grinding elements whereby the grinding elements may be rotated in either direction while permitting their automatic release upon contact of a nail or other obstruction with the grinding elements.

A further object of the invention is the construction of the intermediate driving plate with cam surfaces adapted to co-act with a guard spring to insure the maintenance of the driving plate in either its driving or released positions until changed either by the contact of an obstruction with the grinding elements or when manually reset.

Other objects and advantages will be ap-- parent from the following description, wherein reference is made to the accompanying drawings illustrating a preferred embodiment of my invention and wherein similar reference numerals designate similar parts throughout the several views.

In the drawings:

Fig.- 1 is a central sectional view through a coffee mill equipped with my improved obstruction release intermediate the driving mechanism and the grinding elements.

Fig. 2 is a detail rear elevation of the movable grinding element with the release mechanism mounted thereon and disconnected from the driving shaft.

Fig. .8 is a similar view with the drive plate turned to the position assumed when driving the rotatable grinding element from the driven shaft, but with the retaining spring in openposition.

Fig. 4 is a sectional view taken substantially on the line L 1 of Fig. 1, and showing the drive plate in driving position and with its retaining spring in holding position.

6 is a detail sectional view taken sub stsntially on the line of Fig.

6 is a detail front elevation of the movable grinding element, and

- 7 is sectional view taken substantially on the line T7 of Fig. i.

Referring now to the drawings, the numeral 5 designates the end of a power driven having a projecting tongue 6 thereon adapted to slide in the slot 7 of the driven shaft 8 of a coffee mill. The driven shaft 8 carries a flange 9 on which are fixed a plurality of driving lugs 10 for engagement with the driving plate 11 pivoted on the post 12 eccentrically mounted in the flanged portion 13 of the movable grinding element of the coffee mill. The movable grinding ele ment as herein shown comprises a worm portion 14-v surrounding the end of the driving shaft 5 and adjacent portion-of the driven shaft 8 and the grinding plate 15 secured, as by the screws 16, upon the flanged portion 1-3 of the grinding element. The grinding burrs are suitably arranged upon the front face of the member 15 and co'act with the grinding burrs upon the fixed grinding element 17, which as best shown in Fig. 1, is secured by screws upon the casing 18 of the coffee mill. The casing may be of any de sired shape and size, and is herein shown with a feed spout 19 adapted to receive coffee or other grains from a suitable hopper, and an outlet throat 20 for the ground grains adapted to empty into a. suitable receiving can or bin.

Various degrees of fineness may be imparted to the ground grains by adjusting the distance between the cutting burrs on the fixed and movable grinding elements. As herein shown an adjusting member 21 is arranged to move the driven shaft 8 longitudinally toward and away from the driving shaft 5 whereby the movable grinding element will be advanced toward or withdrawn from the fixed grinding element at will. This adjusting mechanism is not claimed herein, and is shown merely for purposes of illustration.

The driving plate 11 is preferably shaped substantially as shown in Figs. 2-4, and comprises a curved wall portion 11 adapted to. be engaged by one of the lugs 10 on the flange 9 of the driven shaft when said shaft is being driven in the direction of the arrow in Fig. 4. The edge portion 11 of the driv ing plate is also soshaped asto be engaged by one of the driving lugs 10 when the driven shaft aerated the opposite direction from the arrow shown in Fig. 4, and both of the engaging surfaces 11 and 11 are so arranged relatively to the pivot post 12 that engagement by the lugs 10 will tend to reel; the driving plate 11 toward a guard spring 22 pivotally mounted upon the flange 13 of the movable grinding element. This guard spring 22 is sufliciently stiff to prevent the rocking of the driving plate 11 away from driving position under the ordinary power imparted by the driving shaft 5, and suitable adjustingmeans, as for eX- ample the set screw 23 see Fig. 2) may be arranged for regulating the tension upon and position of the guard spring. The adjusting screw 23 is threaded in the flange portion 13 of the movable grinding member and forces the guard spring 22 into engage ment with the abutment 24, and thereafter further turning of the screw 23 will tend to elongate the spring and move its free end toward the driving plate 11. The portion 11 of the driving plate 11 normally adjacent the guard spring 22 is so shaped and positioned that it will contact with the free end of the guard spring as long as normal power is imparted to the rotatable grinding element 13, but will ride over the spring should the member 13 be temporarily stopped, as by engagement with an obstruction. On each side of the portion 11 the driving plate 11 is shaped so that the guard spring will tend to hold the plate in whatever position it then has, whereby the same spring 22 is adapted to maintain the driving plate in released or inoperative position after an automatic release has been effect-ed as well as maintain it in normal driving position. The post 12 on which the driving plate 11 is mounted is eccentrically mounted on the member 13 to permit the swinging of the portion 11 of the driving plate during the resetting operation. I preferably provide a retaining spring for insuring the maintenance of the post 12 in its intended position when the driving plate is set. As herein shown the retaining spring 25 is secured at one extremity in a slot in the post 12 while its opposite extremity normally rests in a notch 26 in the periphery of the member 13. Adjacent one wall of the notch 26 the periphery of the member 13 is cut away to provide a slanting surface down which the spring 25 can be thrown when it is desired to swing the post 12 to facilitate the manual resetting of the driving plate 11.

The operation of my improved mechanism is believed to be apparent. lVhenever the driving shaft is turned, as by an electric motor, movement is imparted to the drivenshaft 8, and through the driving plate 11 to the rotatable grinding member 13 as long as the driving plate is in its normal or operati-ve position as shown in ig. Ad-justments for regulating the fineness of the grains being shown between the fixed and movable burrs of the coffee mill may be made either before or during the grinding operation, without impairing the action of the automatic release mechanism forming the subject matter of this disclosure.

When a nail or other obstruction finds its way between the grinding burrs of the coffee mill its contact with the burrs will retard the movable grinding element 13, and since the driven shaft 8 continues to rotate at the same speed the effect will be to throw an additional force on the driving plate 11 suffcient to enable the lug then in engagement with the driving plate to rock the driving plate to the position shown in Fig. 2 against the tension of the guard spring The portion 11 of the driving plate rides over the free end of the guard spring during such rocking movement of the driving plate, and the guard spring then holds the driving plate against returning to its normal or driv ing position. .r-iccordingly, the driven shaft 3 may continue to rotate without imparting any movement to the grinding element 13. until the driving plate 11 is again reset, and the movable element 13 may stop until the nail or other obstruction is removed from contact with its grinding burrs.

When it is desired to reset the plate 11, the retaining spring is raised out of the notch 28 and slid down the adjacent inclined portion in the periphery of the member 1.3, rocking the eccentric post 12 and swinging the portion 11. of the drive plate away from the guard spring 22. Thereupon the driving plate 11 may be swung from theposition shown in Fig. 2 to the position shown in full lines in Fig. 3, after which the retaining spring 25 is returned to its normal position in'the notch 26. Prior to the manual resetting of the driving plate 11, the obstructions causing the release of the driving plate should be removed from contact with the grinding burrs, but if all obstructions have not been removed, the driving plate will be again automatically tripped when the obstruction re-engages with the grinding burrs as rotation is imparted to the removable grinding element 13.

While it will be apparent that the illus trated embodiment of my invention herein disclosed is well calculated to adequately fulfill the objects and advantages primarily stated, it is to be understood that the invention is susceptible to variation, modification and change within the spirit and scope of the subjoined claims.

Having described my invention, 1 claim- 1. In a device of the character described, a fixed grinding disc, a shaft driven from a. source of power and having a radially spaced projection thereon, a rotatable grinding disc, and means fordetachably connectmg the rotatable grinding disc with the shaft, including a driving plate pivotally mounted on the rotatable disc and adapted to extend into the path ofsaid projection and a guard spring arranged to hold the driving plate in engagement with the shaft projection as long as the power appliedto the driving shaft is below a predetermined maximum and to hold the driving plate out of engagement with the shaft projection after the plate has been swung away therefrom by application of a force greater than the predetermined maximum.

2. In a device of the character described, a fixed grinding disc, a shaft driven from a source of power and having a radially spaced projection thereon, a rotatable grinding disc, and means for detachably connecting the rotatable grinding disc with the shaft, including a driving plate pivotally mounted on the rotatable disc and adapted to extend into the path of said projection and a guard spring arranged to hold the driving plate in engagement with the shaft projection as long as the power applied to the driving shaft is below a predetermined maximum and to hold the driving plate out of engagement with the shaft projection after the plate has been swung away there from by application of a force greater than the predetermined maximum and means for manually swinging the contacting portion of the driving plate away from the guard spring to permit ready resetting of the plate into driving position.

3. In a device of the character described, a fixed grinding disc, a shaft driven from a source of power and having a radially spaced projection thereon, a rotatable grind ing disc, and means for detachably connecting the rotatable grinding disc with the shaft, including a driving plate pivotally mounted on the rotatable disc and adapted to extend into the path of said projection, and a guard spring arranged to hold the driving plate in engagement with the shaft projection as long as the power, applied to the driving shaft is below a predetermined maximum and to hold the driving plate out of engagement with the shaft projection after the plate has been swung away therefrom by application of a force greater than the predetermined maximum, and means for manually swinging the contacting portion of the driving plate away from the guard spring to permit ready resetting of the plate into driving position, including a holding spring arranged to secure said last mentioned means against accidental dislocation during the normal operation of the machine.

4:. In a device of the character described, a fixed grinding disc, a shaft driven from a source of power and having a flange provided with a plurality of circumferentially spaced projections, a rotatable 'rinding disc having a flanged portion encircling the shaft flange, a driving plate pivoted Jon the rotatable disc and adapted to normally extend into the path of said pro ections, said plate having a cam portion spaced from the projections, and a guard spring fixed upon the rotatable disc and arranged to engage one side of said cam portion while the plate is in driving position and the other side there of when the plate has been swung out of driving position.

5. In a device of the character described,

a fixed grinding disc, a shaft driven from a I of said projections, a guard spring fixed upon the rotatable disc and arranged to engage one side of said cam portion while the plate is in driving position and the other side thereof when the plate has been swung out of driving position, and a lever for turning the eccentric post to swing the cam por tion of the driving plate away from the guard spring whenever desired.

6. In a device of the character described, a fixed grinding disc, a shaft driven from a source of power and having a flange provided with a plurality of circiunferentially spaced projections, a rotatable grinding disc having a flanged portion encircling the shaft flange, a driving plate pivoted on an eccentrio post mounted in the rotatable disc and adapted to normally extend into the path of said projections, a guard spring fixed upon the rotatable disc and arranged to engage one side of said cam portion while the plate is in driving position and, the other side thereof when the plate has been swung out of driving position, and a lever for turning the eccentrlc post to swing the cam portion of the driving plate away from the guard spring whenever desired, the flange portion of the rotatable disc being formed with a notch for the reception of one extremity of the lever during the normal operation of the machine.

7. In a device of the character described,

a fixed grinding disc, a shaft driven from a source of power and carrying a radially spaced projection, a rotatable grinding disc loosely mounted on said shaft, and means for detachably connecting the rotatable. grinding disc with said projection including a guard spring and a cammed driving plate pivoted on the rotatable disc, said guard spring being arranged to co-act with the cammed portions of the driving plate to maintain the driving plate ineither its driw ing or released positions.

8. In a device of the character described, a fixed grinding disc, a shaft driven from "source of power and having a flange provided with a plurality of eireun'iferentially spaced projections, a rotatable grinding dise having; a flanged portion encircling the shaft 3 flange, a driving plate pivoted on the rotatable disc and adapted to normally eX- tend into the path of said projections, said plate having; a cam portion spaced from the projections. a guard spring fixed upon the rotatable disc and arranged to engage one side of said cam portion while the plate is in driving position and the other side thereof when the plate has been swung out of driving position, and means for adjusting the tension of the guard spring carried by said flanged portions of the rotatable disc.

In Witness whereof I hereunto set my hand.

WVILLIAM W. DRYDEN. 

